Extends Raphaël 2.0 with set operations to help with manipulating sets

RaphaelExtensions.coffee

# Returns the closest element in the given set.
# Compares the centers of the elements in the set to determine
# the closest element. Returns the Raphaël element closest
# to the point.
# 
# Usage: mySet.closestTo(123,456).attr fill: 'red'
Raphael.st.closestTo = (x, y) ->
    el = null
    dist = Infinity
    @forEach (elm) ->
        box = elm.getBBox()
        delta = { x : box.x + box.width / 2 - x, y : box.y + box.height / 2 - y }
        d = delta.x * delta.x + delta.y * delta.y
        if dist > d
            el = elm
            dist = d
    el

# Returns the index number for the element within a set
#
# Usage: idx = mySet.indexOf el
Raphael.st.indexOf = (el) ->
    Array.prototype.indexOf.call(this, el)

Removed the square root to speed up the loop.